scholarly journals Structure, innervation, mechanical properties and reflex activation of a striated sphincter in the vestibule of the cat vagina

Reproduction ◽  
2009 ◽  
Vol 137 (2) ◽  
pp. 371-377 ◽  
Author(s):  
Roberto Lagunes-Córdoba ◽  
Víctor Tsutsumi ◽  
E J Muñoz-Martínez
Keyword(s):  
Mechanical Properties ◽  
Pressure Wave ◽  
Peak Pressure ◽  
Motor Nerve ◽  
Foley Catheter ◽  
Reflex Response ◽  
Muscle Fibres ◽  
Wave Induced ◽  
Vaginal Sphincter ◽  
Stimulation Of

Vaginal constriction might be important for reproduction in mammals, but existing information is both limited and controversial. This paper shows the structure, mechanical properties, innervation and reflex response of a striated sphincter in the vestibule of the cat vagina. A Foley catheter coupled to a pressure transducer detected in the lumen of the vestibule a pressure wave that was induced by stimulation of the external branch of the motor pudendal nerve. The peak pressure of the wave induced by bilateral stimulation (30.6 cm H2O) was about double of the peak pressure wave induced unilaterally. The tetanus/twitch amplitude ratio was 4.5. The sphincter that produces the increase in vaginal pressure fatigues slowly. Digital, point-to-point summation of unilateral waves was greater than the wave induced bilaterally. Summation of the pressure wave induced by the separate stimulation of the terminal motor branches was also greater than the wave induced by the entire motor nerve. This might reflect multiple innervation of muscle fibres. Single, controlled probing of the vaginal vestibule induced a reflex discharge in the motor nerve. Repetitive probing (10 Hz) induced a motor nerve post-discharge lasting >1 min. The vaginal sphincter is two-half rings of striated muscle fibres in the wall of the vaginal vestibule; the fibres end freely in the dorsal and ventral midlines. Penetration of the vestibule by the penis might trigger sustained contraction of the vaginal sphincter.

scholarly journals The effect of muscular contraction upon the blood flow in the skeletal muscle, in the diaphragm and in the small intestine

1934 ◽  
Vol 114 (788) ◽  
pp. 245-257 ◽  
Keyword(s):  
Skeletal Muscle ◽  
Blood Flow ◽  
Motor Nerve ◽  
Muscular Contraction ◽  
Muscle Fibres ◽  
Direct Stimulation ◽  
Direct Excitation ◽  
Previous Communication ◽  
Arterial Inflow ◽  
Stimulation Of

In the previous communication, p. 233, experiments were described dealing with the effect of contraction of the skeletal muscle upon its blood flow. Short and prolonged tetanic contractions were evoked in various skeletal muscles by stimulation of their cut or uncut motor nerve or by direct stimulation of the muscle. Stimulation of the motor nerve as well as that of the muscle ma involve to an unknown extent the vasomotor innervation of the respective muscles and, although strong evidence was provided that none of the effects observed were even in part due to a direct excitation of the vasomotor fibres, we thought it necessary to repeat our experiments under conditions in which direct excitation of vasomotor fibres is definitely avoided. The present communication describes experiments on the reflex contraction of the tibialis and of the quadriceps femoris (vastocrureus) muscles. So far as we are aware, there is only one reference in the literature which related to circulatory conditions in muscles during a reflex contraction. Denny-Brown (1929), by direct microsopical observations of the surface of the soleus muscle during a stretch reflex, noticed that even a modest amount of pull on the tendon opens up numerous capillaries and hastens the flow of blood in them to a remarkable extent. The tension developed was sometimes as great as 1∙5 kg. Weight. As a result of this observation, Denny-Brown believes that the capillaries are not compressed by the muscle fibres when these contract reflexly. It is, however, quite likely that the circulatory conditions in the superficial layers of the muscle differ from those in the depth of the muscle. Moreover, it is extremely difficult to remove completely all the connective tissue from the surface of the muscle, and we know from Rein's experiments (Keller, Loeser, and Rein, 1930), as well as from our own previous experiments (Anrep, Blalock, and Samaan, 1933), that during the contraction of a muscle there may be considerable dilatation in the resting tissues. In order to determine the total arterial inflow into the tibialis anticus during its reflex contraction, we performed experiments which were similar to those described in our previous communication.

scholarly journals The interaction between two trains of impulses converging on the same motoneurone

1929 ◽  
Vol 105 (738) ◽  
pp. 363-371 ◽  
Keyword(s):  
Mechanical Effect ◽  
The Other ◽  
Muscle Fibres ◽  
Flexor Muscle ◽  
Afferent Pathways ◽  
Afferent Nerves ◽  
Maximal Stimulation ◽  
The Common ◽  
The Relationship ◽  
Stimulation Of

It was shown in an earlier paper (7) that if maximal stimulation of either of two different afferent nerves can reflexly excite fractions of a given flexor muscle, there are generally, within the aggregate of neurones which innervate that muscle, motoneurones which can be caused to discharge by either afferent (i. e., motoneurones common to both fractions). The relationship which two such afferents bear to a common motoneurone was shown, by the isometric method of recording contraction, to be such that the activation of one afferent, at a speed sufficient to cause a maximal motor tetanus when trans­mitted to the muscle fibres, caused exclusion of any added mechanical effect when the other afferent was excited concurrently. This default in mechanical effect was called “occlusion.” Occlusion may conceivably be due to total exclusion of the effect of one afferent pathway on the common motoneurone by the activity of the other; but facilitation of the effect of one path by the activation of the other when the stimuli were minimal suggests that, in some circumstances at least, the effect of each could augment and summate with th at of the other at the place of convergence of two afferent pathways. Further investigation, using the action currents of the muscle as indication of the nerve impulses discharged by the motoneurone units, has now given some information regarding the effect of impulses arriving at the locus of convergence by one afferent path when the unit common to both is already discharging in response to impulses arriving by the other afferent path. Our method has been to excite both afferent nerves in overlapping sequence by series of break shocks at a rapid rate and to examine the action currents of the resulting reflex for evidence of the appearance of the rhythm of the second series in the discharge caused by the first when the two series are both reaching the motoneurone.

scholarly journals VI. —Anaphylaxis and anaphylatoxins

1923 ◽  
Vol 211 (382-390) ◽  
pp. 273-315 ◽  
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Guinea Pig ◽  
Anaphylactic Shock ◽  
The Body ◽  
Muscle Fibres ◽  
Direct Stimulation ◽  
Fundamental Conception ◽  
The Central Nervous System ◽  
Stimulation Of

In the study of the phenomena of anaphylaxis there are certain points on which some measure of agreement seems to have been attained. In the case of anaphylaxis to soluble proteins, with which alone we are directly concerned in this paper, the majority of investigators probably accept the view that the condition is due to the formation of an antibody of the precipitin type. Concerning the method, however, by which the presence of this antibody causes the specific sensitiveness, the means by which its interaction with the antibody produces the anaphylactic shock, there is a wide divergence of conception. Two main currents of speculation can be discerned. One view, historically rather the earlier, and first put forward by Besredka (1) attributes the anaphylactic condition to the location of the antibody in the body cells. There is not complete unanimity among adherents of this view as to the nature of the antibody concerned, or as to the class of cells containing it which are primarily affected in the anaphylactic shock. Besredka (2) himself has apparently not accepted the identification of the anaphylactic antibody with a precipitin, but regards it as belonging to a special class (sensibilisine). He also regards the cells of the central nervous system as those primarily involved in the anaphylactic shock in the guinea-pig. Others, including one of us (3), have found no adequate reason for rejecting the strong evidence in favour of the precipitin nature of the anaphylactic antibody, produced by Doerr and Russ (4), Weil (5), and others, and have accepted and confirmed the description of the rapid anaphylactic death in the guinea-pig as due to a direct stimulation of the plain-muscle fibres surrounding the bronchioles, causing valve-like obstruction of the lumen, and leading to asphyxia, with the characteristic fixed distension of the lungs, as first described by Auer and Lewis (6), and almost simultaneously by Biedl and Kraus (7). But the fundamental conception of anaphylaxis as due to cellular location of an antibody, and of the reaction as due to the union of antigen and antibody taking place in the protoplasm, is common to a number of workers who thus differ on details.

Coxal Muscle Receptors in the Crab: The Receptor Potentials of S and T Fibres in Response to Ramp Stretches

1971 ◽  
Vol 55 (3) ◽  
pp. 813-832
Author(s):  
B. M. H. BUSH ◽  
ALAN ROBERTS
Keyword(s):  
Motor Nerve ◽  
Large Diameter ◽  
Muscle Fibres ◽  
Dynamic Component ◽  
Static Responses ◽  
Basal Joint ◽  
Muscle Receptors ◽  
Shore Crabs ◽  
Static Nature ◽  
Receptor Muscle

1. Intracellular and extracellular recordings from the two large-diameter S and T sensory fibres of the posterior thoracico-coxal muscle receptor in shore crabs confirm the graded, dynamic-static nature of the receptor potentials evoked by stretching the receptor muscle, and the lack of afferent impulses. 2. Slow ramp-function stretches evoke receptor potentials with characteristic shapes, which differ between the two fibres in several respects: (i) The dynamic component in the S fibre resembles an algebraic sum of length and velocity responses and a variable initial ‘acceleration’ (?) transient, while in the T fibre it commonly declines (‘adapts’) during stretching, especially at greater velocities and starting lengths. (ii) On release of stretch the S fibre usually exhibits a ‘negative velocity response’, but the T fibre repolarizes rapidly often with a slight hyperpolarization. (iii) The dynamic response of the T fibre is generally greater than that of the S fibre, and increases more steeply and approximately logarithmically with stretch velocity over a 10- to 50-fold range. (iv) The ‘static response’ or degree of depolarization increases fairly linearly with receptor length in the S fibre but very non-linearly in the T fibre. (v) The T fibre displays pronounced hysteresis in its dynamic and static responses at increasing and decreasing lengths, but the S fibre shows little hysteresis. (vi) The T fibre but not the S fibre commonly shows small rapid oscillations or ‘noise’ superimposed upon strongly depolarized ‘static’ potentials. (vii) The S and T responses may be affected reciprocally by some forms of receptor muscle contraction. 3. Graded receptor potentials evoked in the ‘D’ fibre by stretching the non-muscular depressor-receptor strand of the coxo-basal joint show little hysteresis. 4. Receptor muscle fibres respond to motor nerve stimulation or spontaneous motor impulses from the thoracic ganglion with slow, facilitating and summating excitatory junctional potentials. 5. The mechanisms underlying the differences between S and T responses, and their functional significance to the animal, are discussed, and comparisons are drawn with other muscle receptors.

Homosynaptic depression and transmitter turnover in spinal monosynaptic pathway

1977 ◽  
Vol 40 (1) ◽  
pp. 95-105 ◽  
Author(s):  
R. Capek ◽  
B. Esplin
Keyword(s):  
Transmitter Release ◽  
Motor Nerve ◽  
Drug Effects ◽  
Medial Gastrocnemius ◽  
Lateral Gastrocnemius ◽  
Homosynaptic Depression ◽  
Dorsal Root Reflex ◽  
Frequency Of Stimulation ◽  
Fractional Release ◽  
Stimulation Of

1. The transmission in the spinal monosynaptic pathway was studied during repetitive stimulation of a motor nerve by 10 stimuli at 2, 5, or 10 Hz in spinal cats. Initially, the amplitudes of the monosynaptic responses rapidly declined, reaching a plateau after a few stimuli. The level of the plateau was inversely related to the frequency of stimulation. 2. This depression of monosynaptic response was seen only when the same pathway was stimulated; the response elicited from the lateral gastrocnemius was not depressed when preceded by stimulation of the medial gastrocnemius nerve and vice versa. Pretreatment with semicarbazide left the homosynaptic depression unchanged while suppressing the dorsal root reflex. The participation of a depolarization of primary afferents in the described depression is, therefore, unlikely. 3. The decrease of transmitter release by successive volleys, which is the cause of the observed depression, could conceivably be related to the depletion of transmitter stores. 4. A procedure is described, based on this assumption, which allows the calculation of transmitter turnover. The input-output relation in the spinal monosynaptic pathway is used to convert the amplitudes of monosynaptic responses to the amounts of transmitter, both relative to the maximum response. The changes of transmitter release are analyzed under the assumption that each volley releases instantaneously a constant fraction of the transmitter store available for release and that this store is replenished at a constant fraction of the depleted part per second. 5. The values of fractional release per volley were about 0.4, irrespective of frequency of stimulation. 6. The values of fractional replenishment per second ranged from about 1 to 5 on the average, depending directly on the frequency of stimulation. 7. It is suggested that the described procedure might be useful in analyzing drug effects on synaptic transmission.

Neural, hemodynamic, and renal responses to stimulation of intestinal receptors

1987 ◽  
Vol 253 (5) ◽  
pp. H1167-H1176 ◽  
Author(s):  
L. C. Weaver ◽  
S. Genovesi ◽  
A. Stella ◽  
A. Zanchetti
Keyword(s):  
Sympathetic Nerve ◽  
Reflex Response ◽  
Renal Nerves ◽  
Nerve Activity ◽  
Renal Vasoconstriction ◽  
Pressor Responses ◽  
Fractional Excretion Of Sodium ◽  
Intestinal Receptors ◽  
Renal Responses ◽  
Stimulation Of

Stimulation of visceral receptors with bradykinin has been shown to cause reflex increases in sympathetic nerve activity and systemic arterial pressure. In this investigation, serosal receptors of the intestine were stimulated by bradykinin in anesthetized cats to 1) compare mesenteric and renal sympathetic responses, 2) compare hemodynamic responses in mesenteric and renal beds, and 3) determine changes in renal function. This stimulation in intact animals caused pressor responses, significantly greater excitation of mesenteric than renal nerves, significantly greater mesenteric than renal vasoconstriction, diuresis, natriuresis, and, in denervated kidneys, increases in fractional sodium excretion. In vagotomized, sinoaortic-denervated cats, stimulation of intestinal receptors caused excitation of mesenteric nerve activity greater than renal for only 30 s. This sympathetic reflex response led to pressor responses, equal mesenteric and renal vasoconstriction, diuresis, natriuresis, and increased fractional excretion of sodium only in denervated kidneys. When abdominal perfusion pressure was held constant with an aortic snare in these same animals, the sympathetic reflexes initially caused greater mesenteric than renal vasoconstriction and antidiuresis and antinatriuresis only in innervated kidneys. These findings demonstrate that the intensity of hemodynamic and renal responses to stimulation of visceral receptors correlates well with the magnitude of sympathetic nerve responses.

Jaw Reflexes Evoked by Mechanical Stimulation of Teeth in Humans

1999 ◽  
Vol 81 (5) ◽  
pp. 2156-2163 ◽  
Author(s):  
J. Yang ◽  
K. S. Türker
Keyword(s):  
Mechanical Stimulation ◽  
Masseter Muscle ◽  
Response Pattern ◽  
Bite Force ◽  
Reflex Response ◽  
Incisor Tooth ◽  
Jaw Muscles ◽  
Reflex Responses ◽  
Closing Force ◽  
Stimulation Of

Jaw reflexes evoked by mechanical stimulation of teeth in humans. The reflex response of jaw muscles to mechanical stimulation of an upper incisor tooth was investigated using the surface electromyogram (SEMG) of the masseter muscle and the bite force. With a slowly rising stimulus, the reflex response obtained on the masseter SEMG showed three different patterns of reflex responses; sole excitation, sole inhibition, and inhibition followed by excitation. Simultaneously recorded bite force, however, exhibited mainly one reflex response pattern, a decrease followed by an increase in the net closing force. A rapidly rising stimulus also induced several different patterns of reflex responses in the masseter SEMG. When the simultaneously recorded bite force was analyzed, however, there was only one reflex response pattern, a decrease in the net closing force. Therefore, the reflex change in the masseter muscle is not a good representative of the net reflex response of all jaw muscles to mechanical tooth stimulation. The net response is best expressed by the averaged bite force. The averaged bite force records showed that when the stimulus force was developing rapidly, the periodontal reflex could reduce the bite force and hence protect the teeth and supporting tissues from damaging forces. It also can increase the bite force; this might help keep food between the teeth if the change in force rate is slow, especially when the initial bite force is low.

THE EFFECT OF THYROID HORMONE ON THE RATE OF BOTH NEUROMUSCULAR AND MUSCULAR FAILURE IN ADRENALECTOMIZED MICE MAINTAINED ON SALT

1958 ◽  
Vol 17 (2) ◽  
pp. 134-142 ◽  
Author(s):  
MARY F. LOCKETT ◽  
S. N. GANJU
Keyword(s):  
Thyroid Hormone ◽  
Thyroid Gland ◽  
Nerve Stimulation ◽  
Early Onset ◽  
Dose Effect ◽  
Muscle Fibres ◽  
Rat Diaphragm ◽  
Direct Stimulation ◽  
Normal Rat ◽  
Stimulation Of

SUMMARY Pretreatment of salt-maintained adrenalectomized mice for 6 days with 3–6 mg dried thyroid gland, or with 0·25 μg of either l-thyroxine or l-triiodothyronine, per mouse per day, delayed the early onset of both neuromuscular and muscular failure which are characteristic of these animals. Dose-effect curves for the action of thyroxine on the myoneural junctions and striped muscle fibres are given. A concentration of 0·05μg l-triiodothyronine/100 ml. bath fluid antagonized potassium reduction of the maximal twitch of the normal rat diaphragm in response to nerve stimulation, but not in response to direct stimulation of the curarized muscle.

ATP concentrations and muscle tension increase linearly with muscle contraction

2003 ◽  
Vol 95 (2) ◽  
pp. 577-583 ◽  
Author(s):  
Jianhua Li ◽  
Nicholas C. King ◽  
Lawrence I. Sinoway
Keyword(s):  
Skeletal Muscle ◽  
Electrical Stimulation ◽  
Muscle Contraction ◽  
Motor Nerve ◽  
Muscle Tension ◽  
Nerve Fibers ◽  
Ventral Root ◽  
Ventral Roots ◽  
Root Stimulation ◽  
Stimulation Of

Previous studies have suggested that activation of ATP-sensitive P2X receptors in skeletal muscle play a role in mediating the exercise pressor reflex (Li J and Sinoway LI. Am J Physiol Heart Circ Physiol 283: H2636–H2643, 2002). To determine the role ATP plays in this reflex, it is necessary to examine whether muscle interstitial ATP (ATPi) concentrations rise with muscle contraction. Accordingly, in this study, muscle contraction was evoked by electrical stimulation of the L7 and S1 ventral roots of the spinal cord in 12 decerebrate cats. Muscle ATPi was collected from microdialysis probes inserted in the muscle. ATP concentrations were determined by the HPLC method. Electrical stimulation of the ventral roots at 3 and 5 Hz increased mean arterial pressure by 13 ± 2 and 16 ± 3 mmHg ( P < 0.05), respectively, and it increased ATP concentration in contracting muscle by 150% ( P < 0.05) and 200% ( P < 0.05), respectively. ATP measured in the opposite control limb did not rise with ventral root stimulation. Section of the L7 and S1 dorsal roots did not affect the ATPi seen with 5-Hz ventral root stimulation. Finally, ventral roots stimulation sufficient to drive motor nerve fibers did not increase ATP in previously paralyzed cats. Thus ATPi is not largely released from sympathetic or motor nerves and does not require an intact afferent reflex pathway. We conclude that ATPi is due to the release of ATP from contracting skeletal muscle cells.

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